I guess purchasing a 64GB thumb drive to play music off of it in my CT200h was a bit too optimistic
FAT32 is for a 32GB storage device maximum.. Anything bigger can only be in NTFS or exFAT format which both are not accepted by Lexus.
Partition and reformat the device.
After some googling, I found a free software (for PC) that allowed me to create a partition and reformat the drive. I did with the help of "EaseUS Partition Master 9.2.2"
(NOTE: please be careful where you look for it and make sure you click the right check boxes when installing it to avoid annoying search engines and bugs).
I've partitioned it one to be a 32GB FAT32 drive and the second partition for now is just NTFS.
Hope this helps to those who made the same optimistic decisions like me